“Knuckles” Farrelli is actually in the East End district. The map in the screen shot is the Diamond District but if you look closely you can see the it’s off the map.

– think of Burnley as the north part above the river and the south part below the river.
– go to the most NE corner of south Burnley, it should be the rubble strewn block in the Brainiac Incursion area. It’s also the block just North of the Intergang Penthouse.
– face due east, the investigation is on the SE corner of the first block across the river.

GCPD File on “Knuckles” Farrelli is located in the East End close to the rally point. If you look at the map it looks like there are 2 rally points, but only one is located in the actual East End (lower part of the map).